In recent years, various portable terminals, including personal computers, such as mobile phones and portable game machines have normally carried wireless LAN (Local Area Network) communication capabilities (for example, see Patent Literature 1).
It is specified in a wireless communication system with the IEEE (Institute of Electrical and Electronics Engineers) 802.11 specification that when a portable terminal is intended to be connected to the Internet or the like via an access point, a predetermined procedure called an association between the portable terminal and the access point is performed to allow the access point to identify the presence of the portable terminal.
FIG. 13 is a view illustrating an example of the operating sequence of such a conventional wireless LAN communication system.
The portable terminal broadcasts a probe request including the ESSID (Extended Service Set Identifier) of a network to be connected (step S1300).
The access point replies a probe response when the ESSID included in the received probe request is the same as the ESSID thereof (step S1302). The probe response includes parameters such as the BSSID (Basic Service Set Identifier) of the access point, an encryption method, an authentication method, and a transmission speed.
The portable terminal sends an authentication request to the access point (step S1304).
The access point determines whether or not to authenticate the portable terminal using a predetermined algorithm and replies an authentication response including the results (step S1306). Authentication is carried out generally using the MAC (Media Access Control) address of the portable terminal as an identifier.
The portable terminal confirms the authentication by the access point and then sends an association (connection) request to the access point (step S1308). The association request includes parameters such as ESSID, a support rate, and necessity of poling utilization.
The access point confirms that all the parameters included in the received association request which is an authenticated MAC address are associated with the access point and then sends an association response (step S1310).
Based on the above procedure, the portable terminal can send a data frame (step S1312).